Seashore paspalum ‘SDX-1’

ABSTRACT

A novel seashore paspalum cultivar ( Paspalum vaginatum ) is disclosed. The ‘SDX-1’ cultivar is characterized by having a fine texture, greater sod strength, increased rooting, improved color, improved density, and greater salinity tolerance. The cultivar is particularly well suited for golf courses, grass tennis lawns, lawn bowls, lawns, and athletic fields.

SUMMARY OF THE INVENTION

The present invention relates to a new cultivar of seashore paspalum(Paspalum vaginatum Swartz) that is particularly suited as a turf grassfor recreational fields and golf courses. The new cultivar of thepresent invention is herein referred to by its cultivar name ‘SDX-1’.

The ‘SDX-1’ cultivar is a low growing halophytic grass spreading byrhizomes and stolons. The ‘SDX-1’ cultivar exhibits a dwarf growth habitthat seldom exceeds two inches in mature height under conditions of fullsun. The grass is particularly well suited for use on golf courses forputting greens mowed to ⅛ inch and for fairways mowed to ¼ inch. It isalso suitable for lawns, grass tennis courses, lawn bowls, athleticfields or any other area where a fine textured close mown and lowgrowing turf with superior salt tolerance is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a comparison of the inventive cultivar with a Floridanative (natural) ecotype and four improved turf-type varieties. Thesevarieties, from left to right, are Florida native type, ‘SeaIsle 1’(University of Georgia release), Applicants' variety ‘SFX-14’ (Ser. No.09/502,903), Applicants' variety ‘SGX-6’ (Ser. No. 09/502,904), andApplicant's seashore paspalum variety named ‘SDX-1’.

FIG. 2 shows seedheads form various seashore paspalum varieties. Thesevarieties, from left to right, are Florida native type, ‘SeaIsle 1’(University of Georgia release), Applicants' variety ‘SFX-14’,Applicants' variety ‘SGX-6’, and Applicant's seashore paspalum varietynamed ‘SDX-1’.

FIG. 3 is a photograph of stolon sprigs of the ‘SDX-1’ variety (#4)compared to other seashore paspalum varieties (#1=native seashorepaspalum; #2=applicants' ‘SFX-14’ variety; and #3=applicants' ‘SGX-6’variety).

FIG. 4 is a photograph of the ‘SDX-1’ variety 4 weeks followingsprigging.

FIG. 5 is a photograph of the ‘SDX-1’ variety (unmown) 12 weeksfollowing sprigging.

FIG. 6 is a photograph of the ‘SDX-1’ variety (unmown) 32 monthsfollowing establishment.

DETAILED DESCRIPTION OF THE VARIETY

The following is a detailed description of the new grass variety basedupon observation of the grass grown in field plots and under live golfconditions on a local golf course.

Asexual Reproduction

The ‘SDX-1’ grass was developed by the applicants on Pine Island, Fla.in a saline environment. Early ecotypes from the applicants' turfdevelopment program were developed from crosses between Florida nativeecotypes and ‘Adalayd’ (U.S. Plant Pat. No. 3,939) seashore paspalum.‘SDX-1’ was developed by crossing applicants' improved turf-typeecotypes and subsequent evaluation of the resulting progeny. Trial areasof the grass were established and maintained under live golf conditionsat Alden Pines Country Club, Bokeelia, Fla. (a salt water irrigated golfcourse) since 1997. This grass has been asexually propagated by theapplicants as sprigs, plugs, and sod, and remain true to type insubsequent asexual reproductions, subject to damage from externalfactors, as discussed further below.

Botanical description

The age of the cultivar observed for the following botanical descriptionwas about 180 days. All color descriptions with respect to parts of thecultivar, where color is a distinguishing feature, are made to theMunsell Color Chart, except where terms of ordinary usage and dictionarymeaning are used. The ‘SDX-1’ cultivar is a perennial grass. The grassstems have overlapping sheath margins and arise from an extensive systemof long, straw colored, slender rhizomes and/or purple-tinged stolons.The grass blades are glabrous and folded, forming a V-shape. The grassblades have an olive green color, Munsell color designation 7.5 GY 4/6(abaxial side) and 7.5 GY 5/4 (adaxial side). The blade length isgenerally 0.5-1.6 cm (unmown). The blades have a typical width of from1.75 to 3.0 mm, varying with the level of salinity and tapering to aninvolute apex. Leaf-blade venation runs parallel without cross veins.The veins are obscure with a prominent mid-vein. The leaf margins aresmooth. Leaf-sheath auricles are absent. The ligules have an eciliatemembrane. External ligules are not present on the collar. Uponflowering, the culms are about 0.5-4.5 cm tall (most are 1.5-2.5 cmtall) with terminal inflorescence subtended by an unspecializedleaf-sheath. Inflorescence bears well-developed spikelets forming pairedbranches (racemes) at the culm apex about 0.6-1.6 cm in length. Theracemes each have a broad, triangular rachis bearing two rows ofspikelets (one floret per spikelet). The rachis are angular and narrowlywinged. The rachis, which are tough and persistent, are also about 1-2mm in width, and terminate in a spikelet. Spikelet packing is regular,two-rowed, abaxial, and contiguous, with subequal internodes.

Florets (seed) are ovate and about 0.4-0.75 mm in diameter. Glumes,palea, and lemma are awnless, glabrous, and green with an acute apex.

Leaf blade with and length of the ‘SDX-1’ cultivar are affected by bothsalinity level and by the length of sunlight exposure. It produceslonger narrower leaf blades in winter compared to shorter, wider leafblades in summer. Likewise, as salinity levels increase, shorter,narrower, and somewhat more erect leaf blades are produced, compared tolonger wider blades produced upon irrigation with a fresh water or lowsalinity system.

General Observations

This grass has shown to be particularly well suited for use on puttinggreen surfaces due to the high shoot density, short internode length,short blades and fine texture produced under close mown conditons andsaline irrigation. Due to its inherent dwarf growth form, this grass isalso suited for use on high-quality lawn areas where an infrequentmowing regime is utilized, seldom exceeding 2 inches in overall heightunder unmown conditions in full sunlight. While ‘SDX-1’ exhibits dwarfgrowth form with short internode length and overall low vertical growthhabit, the grass grows very vigorously and densely in a horizontalfashion and quickly forms a dense sod when established from sprigs. Thisgrass has been tested under regular saline irrigation up to 26,000 ppm.Trials have been conducted applying 45,000 ppm (brine) salinity water toputting green surfaces established with this grass for weed and pestcontrol. Target organisms have been eliminated with the brine waterapplication with no apparent visual damage to the grass. Directapplications of table salt or sea salt has also been employed for weedcontrol although temporary burning of the grass leaf tips may beobserved with heavy salt applications.

SDX-1 develops an extensive rhizome system composed of primary rhizomes,with secondary and tertiary rhizome branches arising from the primaryrhizomes. As the turf stand matures, the primary rhizomes will storeappreciable carbohydrate reserves and become thickened and somewhattuberous with the leaf shoots typically originating exclusively from thesecondary and tertiary rhizome system. In the event that the turf isdamaged such that loss of leaf shoots and rhizome branches occur, newleaf shoots may be initiated from nodes on the primary rhizomes. If suchan event does occur, the initial leaf shoots arising from the thickenedprimary rhizomes will initially be larger and coarser than leaf shootstypical of the SDX-1 cultivar. As the turf recovers from the damage, andnew rhizome branches are developed, the resultant leaf shoots will betypical of the SDX-1 cultivar as described. Restoration of thefine-textured leaf shoot system typical of the SDX-1 cultivar may beenhanced by common turf cultural practices, such as mowing andverti-cutting.

Damage to the turf that may result in leaf shoots emerging from primaryrhizomes typically includes insect damage, disease damage, or damagefrom chemical burning (e.g. oil spill).

Thickened, primary rhizomes as described are typically 4 to 5 mm indiameter. Leaf blades from any emerging leaf shoots arising from suchrhizomes are from about 4 to 5 mm in width, corresponding to thediameter of rhizome, and about 2 to 3 cm in length. Secondary rhizomebranches are typically 1.5 to 3 mm in diameter, and tertiary rhizomebranches are typically 0.75 to 1.5 mm in diameter. The primary rhizomestypically develop with some depth in the soil profile, from 4.75 to 10cm in depth (occasionally up to 15 cm depth). Secondary and tertiaryrhizome branches develop throughout the rhizome profile depth, with leafshoot initiation typically restricted to those rhizomes within the 0 to4 cm soil profile depth range.

Compared to ‘Adalayd’ (‘Excalibre’) seashore paspalum utilized forsimilar purposes, this grass has foremost greater salinity tolerance,and under saline conditions, improved density, finer texture, greatersod strength, increased rooting and improved color. Compared to otherseashore paspalum turfgrass ecotypes developed by the applicants',‘SDX-1’ is a compact, dwarf form that forms a low, dense, tight sod evenunder unmown conditions. Compared to other fine textured grass species(notably common and hybrid bermudagrass) for similar use, this grass hasadaptations for moderate shade tolerance and enhanced temperaturetolerance, retaining color at lower temperatures than bermudagrasses.This grass has a lower water use requirement compared to St. Augustineand hybrid bermudagrass cultivars and has enhanced qualities for droughttolerance and can be grown in sandy soils as well as in heavy-texturedwaterlogged soils.

We claim:
 1. A new and distinct cultivar of seashore paspalum grass,substantially as herein illustrated and described, characterized by itsfine texture when closely mown, its superior tolerance to salt, drought,and soil hypoxic conditions, and its low, dwarf growth